In many industrial applications, such as the manufacture of foods and beverages, hard surfaces commonly become contaminated with soils such as carbohydrate, proteinaceous, and hardness soils, food oil soils and other soils. Such soils can arise from the manufacture of both liquid and solid foodstuffs. Carbohydrate soils, such as cellulosics, monosaccharides, disaccharides, oligosaccharides, starches, gums and other complex materials, when dried, can form tough, hard to remove soils, particularly when combined with other soil components such as proteins, fats, oils and others. The removal of such carbohydrate soils can be a significant problem. Similarly, other materials such as proteins, fats and oils can also form hard to remove soil and residues.
Food and beverage soils are particularly tenacious when they are heated during processing. Foods and beverages are heated for a variety of reasons during processing. For example, in dairy plants, dairy products are heated on a pasteurizer (e.g. HTST—high temperature short time pasteurizer or UHT—ultra high temperature pasteurizer) in order to pasteurize the dairy product. Also, many food and beverage products are concentrated or created as a result of evaporation.
Specific examples of food and beverage products that are concentrated using evaporators include dairy products such as whole and skimmed milk, condensed milk, whey and whey derivatives, buttermilk, proteins, lactose solutions, and lactic acid; protein solutions such as soya whey, nutrient yeast and fodder yeast, and whole egg; fruit juices such as orange and other citrus juices, apple juice and other pomaceous juices, red berry juice, coconut milk, and tropical fruit juices; vegetable juices such as tomato juice, beetroot juice, carrot juice, and grass juice; starch products such as glucose, dextrose, fructose, isomerose, maltose, starch syrup, and dextrine; sugars such as liquid sugar, white refined sugar, sweetwater, and inulin; extracts such as coffee and tea extracts, hop extract, malt extract, yeast extract, pectin, and meat and bone extracts; hydrolyzates such as whey hydrolyzate, soup seasonings, milk hydrolyzate, and protein hydrolyzate; beer such as de-alcoholized beer and wort; and baby food, egg whites, bean oils, and fermented liquors.
There are generally at least two sides to an evaporator. One side holds the steam or vapor heat source (typically 212° F. to 350° F.). The other side holds the process liquid to be concentrated. During the evaporation process, the liquid to be concentrated is introduced into the evaporator. The heat exchange across the tubes or plates evaporates water off the process stream concentrating the liquid solids. The liquid to be concentrated may be run through an evaporator several times until it is sufficiently concentrated.
There are many different types of evaporators including falling film evaporators, forced circulation evaporated evaporators, plate evaporators, circulation evaporators, fluidized bed evaporators, falling film short path evaporators, rising film evaporators, counterflow-trickle evaporators, stirrer evaporators, and spiral tube evaporators. In addition to the evaporators, there are several other pieces of equipment in an evaporation plant including preheaters and heaters, separators, condensers, deaeration/vacuum systems, pumps, cleaning systems, vapor scrubbers, vapor recompression systems, and condensate polishing systems. All of the evaporation plant equipment should be cleaned, however, the actual evaporator typically has the most difficult soiling problems.
When a food or beverage product contacts any surface, soiling occurs where some part of the food or beverage product is left behind on that surface. When that surface is a heat exchange surface, the soil becomes thermally degraded rendering it even more difficult to remove. Over time, the layer of soil increases in thickness as more food or beverage product is passed over the heat exchange surface. The layer of soil acts as an insulator between the heat and the product being heated, thereby reducing the efficiency of the heat exchange surface and requiring more energy to create the same effect if the heat exchange surface were clean. When the heat exchange surface is an evaporator, the difference between a clean heat exchange surface and a soiled heat exchange surface can mean the difference in millions of dollars in energy costs for an evaporator plant. With the cost of energy increasing significantly, as well as an increased awareness of protecting the environment by preserving natural resources, there remains a need for cleaning programs that can clean heat exchange surfaces and create an efficient transfer a heat.
Clean-in-place cleaning techniques are a specific cleaning regimen adapted for removing soils from the internal components of tanks, lines, pumps and other process equipment used for processing typically liquid product streams such as beverages, milk, juices, etc. Clean-in-place cleaning involves passing cleaning solutions through the system without dismantling any system components. The minimum clean-in-place technique involves passing the cleaning solution through the equipment and then resuming normal processing. Any product contaminated by cleaner residue can be discarded. Often clean-in-place methods involve a first rinse, the application of the cleaning solutions, a second rinse with potable water followed by resumed operations. The process can also include any other contacting step in which a rinse, acidic or basic functional fluid, solvent or other cleaning component such as hot water, cold water, etc. can be contacted with the equipment at any step during the process. Often the final potable water rinse is skipped in order to prevent contamination of the equipment with bacteria following the cleaning and/or sanitizing step.
Clean-in-place processing requires a complete or partial shutdown of the equipment being cleaned, which results in lost production time. Many times, the equipment is not thoroughly cleaned, due to the large downtime needed. What is needed is an improved method for cleaning this equipment, using the clean-in-place process, which uses less time to thoroughly remove the soils.
It is against this background that the present invention has been made.